Conventionally, various piston designs have been made in correspondence with places of destination and engine displacements (e.g., Japanese Patent Publication No. 7-86336). Since the shape of a piston can be changed more easily than a cylinder block and the like, the piston shape often undergoes flexible design changes for the purpose of realizing a target compression ratio, emission performance, and the like.
It is a common practice to design a piston using computer software such as CAD and the like.
However, conventionally, either of a method of creating a two-dimensional (2D) design drawing alone and a method of creating three-dimensional (3D) data that represents the shape of the entire piston from the beginning, and converting it into 2D data is adopted.
However, in case of piston design, only 3D view allows verification of interference among surrounding components. Nevertheless, if verification is made upon forming the shape of the entire piston on a 3D space from the start, when a problem is detected as a result of verification, the re-design load is heavy, resulting in poor design efficiency.